Fluid fuel burner control system



May 23, 1939.

c. GVKRONMILLER FLUID FUEL BURNER GONTROL SYSTEM Filed April 15, 1936 l-zventor' arl G. Kforzwzllef 1 J/fzwf sw Patented May 23, 1939 PATENT 4OFFICE t FLUID FUEL BURNER CONTROL SYSTEM Carl G. Kronmiller, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a. corporation voi Delaware Application April 15, 1936, Serial No. 74,481

1 Claim.

My invention relates to a uid fuel burner control system and more particularly to such a system wherein the flow of fuel to the main burner is controlled by a valve actuated by a pressure motor.

In systems of this type it is the usual practice to provide one or more control or pilot valves which regulate the pressure exerted upon the pressure motor and hence control the opening c and closing of the fuel valve. Where the opening and closing of the fuel valve is lto be controlled by several conditions, such as by the space temperature and the presence or absence of a flame in the pilot burner, it has been the usual customv to provide as many control valves as there are controlling conditions. This is particularly true where the condition responsive devices mechanically actuate the control valves. Such provision of a plurality of control valves materially adds to the expense of the installation and increases the number of moving parts which can get out of order. It has further been the practice where the flow of gas to the pilot is controlled by a thermostat responsive to the presence or absence of a flame in the pilot, or in other words, by a safety v pilot, to provide a separate by-pass valve for admitting gas to the pilot and initially starting up the apparatus. With such structures the by-pass valve is held open until the pilot has become sufflciently heated to permit the safety pilot to open the main pilot burner valve.

An object of the present invention is to provide a fuel burner control system of the general type discussed wherein a pressure control valve is `provided for regulating the pressure exerted on the pressure motor and a pilot burner valve is provided for controlling the ilow of gasto the pilot, in which system a device responsive to one condition, such as the temperature of the space being heated, controls the position of the control valve and in which a second condition responsive device responsive to the presence or absence of a ame inthe pilot burner operates to both close the pilot burner valve and to move the control valve to a position wherein the main valve is closed upon the extinguishment of the pilot burner.

A further object of the present invention is to provide a system of the type mentioned in the previous paragraph wherein manually operable means are provided for opening the pilot burner valve without disturbing the position of either the device responsive to the presence or absence of a dame in the pilot burner or the control valve which controls the position of the main valve.

A further object of the present invention is to provide a fuel burner control system of the type in which the ilow of fuel to the main burner is controlled by a valve actuated by a. pressure motor wherein a single control valve is provided for regulating the pressure in the pressure motor and consequently the opening and closing of the main valve and wherein said control valve is normally controlled by one condition'responsive device andin the event of a critical condition is moved by another condition responsive device to a position wherein the main-valve is closed.

Further objects of the present invention will be apparent from a consideration of the accompanying specification, claim and drawing, of which Figure l is a view partly in section of a preferred form of my burner control system and in which t Figure 2 is a detailed View of a portion thereof on an enlarged scale relative to Figure 1.

While my invention is not to be limited to any particular Aapplication of my control system, the burner is shown for purposes of illustration as located in a type of unit heater commonly known in the art as a space heater.

'Ihe drawing shows only a fragmentary view of the front wall of this heater, which wall is designated by the reference numeral IIJ. A portion of a main burner is designated by the reference numeral Il and is supplied with gas from a main I2 through a conduit I3, the flow through which is controlled Vby a valve I 4. Means 9 are provided for admitting air to the gas supplied to the burner to form a combustible mixture of the proper characteristics.

The valve I4 comprises a valve casing having upper and lower portions I5 and I6, respectively. The lower portion I6 comprises lthe usual valve inlet I1 and valve outlet I8. Extending between the inlet and outlet portions I'I and I8 is a partltion I9 which is apertured at 20 to' provide a valve seat upon which is adapted to seat a valve disk 2|.

Clamped between the upper and lower portions I5 and I6 of the valve housing is a diaphragm 22, which diaphragm forms a movable wall of a pressure motor, as Will be more apparent from the accompanying description. Located on opposite sides of the diaphragm are counterweight members 23 and 24 which are clamped together through a threaded member 25 and clamping nuts 26 and 21. 'I'he member 25 serves to connect the valve disk 2| with the diaphragm 22. An aperture 28 extends through both counterweights 23 and 24 and through diaphragm 22. It will readily be seen that the diaphragm 22 divides the valve housing into two chambers 29 and 30 which are separated from each other with the exception of the passage 28,'which permits a limited amount of iluid to fpass between the two sides of the diaphragm.

A pilot burner 32 is located adjacent the main burner I I in the customary manner to constitute the igniting means for the burner. This pilot burner is connected to the inlet side of the main valve I4 through a pipe 33. 'I'his connection is controlled by a pilot burner valve 34. This pilot burner valve may be of any suitable construction and comprises a valve disk 35 to which is secured an elongated valve stem 36. Suitable passages 31 are provided in the pilot burner for the admission of air thereto.

A control valve for the main valve |4 is generally designated by the reference numeral 38. This control valve is located in a boss 39 oi' the valve housing. 'Ihe valve seat 40 is located at one end of a chamber 46 in the boss 39, which chamber is sealed at its other end by a gland nut 4| which is threaded into the boss 39. A valve head 42 cooperates `with the valve seat 46 and is actuated by means of an elongated valve stem 43. The valve seat 40 is in communication with the upper chamber 30 through a passage 44 extending through the upper wall of the upper portion i5 of the valve housing. Extending transversely into boss 39 and communicating with the chamber 46 is a bleed pipe 45, which bleed pipe leads from said valve to av point adjacent the upper portion of the pilot burner 32. It will be readily seen that when the valve 38 is in the closed position as shown no gas can escape from the upper chamber 30 but that when the valve is open, gas can pass out through passage 44, chamber 46 and pipe 45 to the outlet of the pilot burner where it is consumed. Valve 38 accordingly regulates the pressure upon the upper side of the diaphra`gm 22 and controls the action oi' the main valve I4 in a manner to be more fully pointed out hereinafter.

Located on the front wall I of the heater in which the burner vIl is located is a thermostat housing which housing is mounted on a member 5|, which serves to space the housing 50 outward from wall I6. Member 5| is provided with apertures 52 to permit free circulation o! air between the heater wall lI0 and the thermostat housing 50 so as to prevent the thermostat from being directly affected by the heater temperatures.

The thermostat 50 comprises a housing formed of a base member 54 and a shell member 55. The shell member 55 is provided with suitable apertures 56 to permit access of the air in the room to the thermostatic element. The thermostatic element is designated by the reference numeral 51 and comprises a more or less conventional looped member of bimetallic material. This bimetallic element 51 is mounted on base 54 through any suitable mounting block 58. Through the upper portion of the outermost leg of bimetallic-'element 51, a valve stem 43 is extended. At the point where the valve stem' 43 extends through bimetallic element 51, portions of the bimetallic element are struckoutwardly on each side as designated at 59 and 60. Nuts or other suitable fastening means 6| and 62 serve to secure the `valve stem 43 to the bimetal 51 so that any movement of the bimetal 51 is immediately transmitted to valve stem 43 and accordingly to the valve 38 through valve head 42. 'Ihe struck-out portions 59 and 60 being slightly curved serve to form curved bearing surfaces for nuts 6| and 62 and permit a slight pivoting of the valve stem 43 as the ,bimetallic element changes its angular position. As indicated by Aa legend onthe drawing,'the bimetallic element is so arranged that when the temperature rises, the outermost leg thereof to which the valve stem 43 is attached is moved to the left and when the temperature drops, the reverse action takes place.

Mounted upon the pilot burner 32 is a bimetallic element 65, which bimetallic element is secured to the burner through a mountingblock 66. A slot 61 is located in the upper portion of the pilot burner adjacent the upper end of the bimetallic element 65. When the pilot burner is lit. ame will issue from the slot 61, which ame will play-over the upper end of the bimetallic element 65 and heat the same. As indicated by the legend upon the drawing, the heating of the bimetallic element in this manner causes the right leg of the bimetallic element to move to the right.

Mounted on the valve stem 36 is a collar 10. Abutting against thiscollar is a spring 1| which is intended to engage the bimetallic element 65. A pin 12 passes through the valve stem 36 and is designed to limit outward expansion of spring 1|. As indicated more clearly in Figure 2, the bimetallic element 65 is provided with an elongated slot 14 which slot is of such shape and so disposed as to permit pin 12 to freely pass therethrough but is sufiiciently narrow to prevent spring 1| from passing therethrough. 'Ihus in the position shown, the spring 1| bears against the bimetallic element 65. However, if the bimetallic element 65 by reason of being heated is deflected sufficiently to the right so as to permit spring 1| to engage pin 12, the bimetallic element 85 may move away from spring 1|.

The pilot burner valve stem 36 extends through the wall I6, member 5|, base 54, bimetallic element 51, and shell 55 and has attached in the front end thereof a knob 15 designed for manual actuation of the pilot burner valve stem 36. Also attached to the stem 36 is a collar 11 and located between this collar 11 and the base member 65 is a spring 18 which bears against the collar 11 and serves to bias valve 34 to an open position. Thus upon bimetallic element 65 being deected sufilciently to the right to move away from engagement with spring 1|, spring 18 is effective to move the valve disk 35 away from its seat and to open the pilot burner valve 34 admitting gas to the pilot burner. Moreover, even when the pilot is -cold, the pilot valve 34 may be opened by grasping knob 15 and pulling valve stem 36 outwardly against the action of spring 1I. 'I'his operation will be more fully described in a subsequent paragraph.

Connected to the control valve stem 43 is a collar 83 which is similar in, function and form to collar 10 of valve stem 36. Likewise, extending through a valve stem is a pin 8| which serves to limit the outward expansion of a spring 82, which spring is shown as bearing against bimetallic element 65. As will be apparent from Figure 2, the construction is substantially the same as that described for valve stem 36 and, as in the previous case, an elongated opening 84 is provided which is of such shape as to permit the pin 8| tol move therethrough but to prevent the spring 82 from passing therethrough. Thus as the bimetallic element 65 is deected sumciently to the right, it will move away from engagement with spring 82 and leave the valve stem 43 under the sole control of the thermostatic element 51.

The operation of my fuel burner control system will now be described. In the positions shown in the drawings, all the burners are extinguished and the main valve, the control valve 38 and the pilot burner valve 34 are closed. The main valve is held closed by pressure in the upper chamber 36. This pressure arises by the fact that gas from the underside of diaphragm 22 which is opposed to the fuel line pressure has passed through the aperture 28 into chamber 3|) wherefrom it cannot escape by reason of valve 38 being closed. The accumulation of this gas inthe upper chamber causes the pressure on the two sides of the diaphragm 22 to be equalized with the result that the valve is moved to closed position by reason of the action of counterweights 23 and 24. The valve disk 2| will remain seated against valve seat 28 until the control valve 38 is opened.

When it is desired to start theburner up, knob 15 is grasped and pulled outwardly so as to open the pilot burner valve 34 against the action of spring 1| as described previously. This permits gas to ow to the pilot burner 32 where it may l be ignited as it issues'from burner openings 86. Knob 15 is held outwardly until the bimetallic element V65 constituting the safety pilot has become suiiiciently heated so as to move away to the right suiliciently to move out of engagement with spring 1|. When this has taken place, the biasing action of spring18 will act to hold valve 34 open after the knob 15 has been released.

At the same time as bimetallic element 65 moves away from spring 1|, it also moves away from spring 82 permitting the valve stem 43 to be placed under the control of the thermostat 50. If the temperature of the space in which the heater is located is below the desired value,. the long leg of bimetallic element 51 will beV subjected to a force tending todeect itsuiliciently to the right so that as soon as the control of valve stem 43 by pilot 85 is terminated, the bimetallic element 51 will'be operative to move valve stem 43 to the right and open control valve 38. As soon as this takes place, the upper chamber 30 is placed into communication with bleed pipe 45 and the gas therein is released through bleed pipe 45 wherein it is consumed by the pilot burner. Due to the fact that the size of the bleed pipe in passage 44 is so much larger than the restricted passage 28, gas will pass out through the bleed pipe much more rapidly than it can pass from the underside of the chamber to the upperside thereof so that no appreciable pressure will exist in the upper chamber 38. -This will result in the pressure of the gas on the underside of the diaphragm being effective to raise the diaphragm and move the valve to open position. This permitsgas to flow from the supply pipe I2 through pipe I3 to the burner where itis ignited by the flame issuing from pilot burner opening 88.

During the normal operation of the device, the biuner will. remain in operation untilthe space temperature has become suiiiciently heated by reason of the operation of the burner as to deflect the elongated leg of bimetallic element 51 l to the left so as to close control valve 48. The closing of control valve 40 will of gas through bleed pipe 45 and pressure will be built up in the upper chamber which will be eective to close the main valve.v The main valve will thus be successfully opened andclosed in accordance with the temperature in the space being heated by the main burner.

In the event of the pilot. 32 becoming extinguished in the meantime,` or in other words3 when the igniting means fails and accordingly is not available for the purpose-of igniting the main burner being terminated, the flame issuing from opening 61 will similarly become extinguished and will cause the bimetallic element 85 to assume .the tion shown in the drawing. In view of the ""ing the pilot burner ment of my invention,

prevent the-escape Bcl; that bimetallic element Il is constructed of much more rigid material than bimetallic element 51, it is able to overpower they# and acting i action of bimetallic element 51 I" through spring 82 is able to close thecontrol vvalve 38 even though the thermostaticelement 51 may be in a posiiton where the control valve 38 would otherwise be open, or in other words, even though the thermostat 58 may be calling "for heat. At the same time, the bimetallic element 65 acts through spring 1| to close the pilot burner valve 34. The result is that the supply of gas to both the main burner and pilot burner is cut ofi'. Due to the fact that the pilot responsive thermostat 65 is of much more rigid construction than the mainY thermostatic element 51, as previously pointed out, it is impossible to reopen the main gas valve u'ntil the pilot burner -is again lit by operation of the knob 15 in the manner previously described.

It will thus be seen that the control valve 38 is controlled by both the thermostatic element 51 and the thermostatic element 65, the control being effected in such a manner that when the thermostatic element 65 which is responsive to the presence or absence of a pilot flame is in vits hot position, the valve 38 is controlled solely by thermostat 58. However, when the pilot is extinguished, the thermostatic element 85 is effectlve to take the control away from thermostat 50 and to close control valve 38 regardless of whether thermostat 581s. calling for heat or not. At the same time the pilot burner valve is extinguished to prevent a flow of gasto the `pilot. Moreover, means are provided for openvalve without disturbing the position of the pilot responsive thermostatic element. 'I'here is thus avoided the necessity of a plurality of control valves for the main gas valves and at the same time, I avoid the necessity of providing a by-pass for admitting gas to the `pilot in starting up.

While I have shown a. certain it will be understood that this is for purposes of illustration only and that my invention is to be of the appended claim.

I claim as my invention:

In a fluid fuel burner control system, a main burner, a pilot burner, a main valve controlling the flow of fuel to said main burner, a pressure.

motor for operating said main valve, means for supplying a pressure uid to said motor to operate the same, a control valve for controlling the pressure in said motor, said pressure motor being operative when said control valve assumes a rst position to move said main valve to open position and when said control valve assumes a second posi-tion to move said main valve to closed position, means responsive to a controlling condition for varying the position of said control valve, a. pilot burner valve controlling the ow of fuel to said pilot burner, means responsive to the presence of a llame at'said pilot burner and directly operative to move said control valve to said second position and to close said pilot burner valve in the absence of a flame at said pilot, said last named means be- CARL G.

limited only by the scope specic embodiing connected to said pilot burner valve throughl 

